Upwards of 400,000 people in the US experience cardiac arrest annually, and the implantable cardioverter- defibrillator (ICD) has transformed the care of patients at risk for these potentially fatal arrhythmias. The results of recent clinical trials have led to an expansion of the indications for ICD therapy, and it is estimated that over 500,000 patients will receive these devices annually. While ICDs can be life saving, significant adjustment problems and impaired quality of life (QOL) can arise as a function of ICD shock frequency. Further, adjustment problems increase the likelihood of arrhythmias requiring shock for termination. Working in the laboratory and in the natural setting, we have identified the experience and response to acute emotional stress as specific vulnerabilities to the occurrence of arrhythmias that require shock for termination. We have therefore identified a potential target for intervention - mental/emotional stress - to reduce vulnerability to arrhythmia requiring shock in patients with ICD. Stress reduction treatments have been shown to reduce vulnerability to emotion-triggered ischemia, and improve event free survival after ACS. Therefore, the Specific Aims of the proposed study are to test, in a randomized clinical trial with new ICD patients, the effects of a stress reduction intervention (SRT) on, 1) shock-treated arrhythmia, 2) arrhythmogenic electrophysiological (EP) changes during acute stress in the laboratory, and, 3) Quality of Life. A total of 304 patients will recruited while in hospital at the time of ICD receipt and be randomized to usual care or a 12-week, group based, cognitive behavioral stress reduction treatment (SRT). Primary endpoints include shock treated arrhythmia event-free survival over 2 years, pro-arrhythmic EP changes during laboratory mental stress, 24-hour heart rate variability, and quality of life. Secondary endpoints include anti-arrhythmic medication changes, hospitalizations, deaths, and psychological measures of anger. RELEVANCE: Confirmation of hypotheses concerning the benefits of SRT treatment could transform the care of ICD patients. Patients receiving these devices could be offered SRT prophylactically to reduce the risk of arrhythmia requiring shock for termination. In addition, should the effect of SRT be particularly greater for those patients prone to anger, ICD patients at risk due to anger could be identified prospectively, and SRT particularly targeted to them.